Apparatus for the preparation of fertilizer material



June 14, 1955 E. J. DOUGLAS 2,710,423

APPARATUS FOR THE PREPARATION OF FERTILIZER MATERIAL Filed Aug. 25, 195:I s Sheets-Sheet 1 INVENTOR. E dwin J Douglas 1!: g. 8 'A TTOENE Y5 M4.4

'A MEMBEE OF THE F June 14, 1955 E. J. DOUGLAS 2,710,423

APPARATUS FOR THE PREPARATION OF FERTILIZER MATERIAL Filed Aug. 25, i953s Sheets-Sheet 2 6 Jig? I 4/ 64 9 o I D II D a Q //8 o 9 0 I"! UP 4 //28 m 9 1/ i a o 2 m m {Z Q E .4/3 JII J Q ma $419.7 k INVENTOR.

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June 1955 E. J. DOUGLAS APPARATUS FOR THE PREPARATION OF FERTILIZERMATERIAL I 7 Filed Aug. 25', 1953 8 Sheets-Sheet 8 INVENTOR. fanll'n1,000 /a .s Zak/MFA? 5 $4 mac,

nrrozlve'va A @5442": of rye F/(M June 1 5, 1955 APPARATU FQR THEPREPARATION 0F FERTILEZER MATERIAL Edwin ll. Douglas, Whittier, Calif.,assignor to Staul fer Chemical Company, a corporation of DelawareApplication August 25, 1953, Serial No. 376,351

17 Claims. (Cl. Li -1) This invention relates to an apparatus for theformation of finely divided solid materials into spheres of a desiredsize. The term granulation is frequently applied to processes of thisnature which are practiced upon such materials as fertilizers, catalystsand the like. Usual methods of granulation include wetting of the solidsto be granulated with a liquid and rolling of the mass upon itself whiledrying the mass, as by subjecting it to a flame projected into therotary tube. This process is subject to objection in that the product iscomposed of hard encrusted particles of irregular size and shape. If auniform product is required, the fines and oversize must be separatedand returned for further processing; this recycle burden contributesconsiderable undesirable cost to a process of granulation.

in accordance with the present invention, 1 provide an apparatus whichenables finely divided materials to be formed into spheres of uniformsize, the uniformity being such that, depending on the exact conditionsof operation, as much as 95% of the spheres will be substantially thesame diameter, thus reducing the recycle burden. Further, the particlesare generally of uniform hardness and density and do not have a hardencrusted shell and are spheroidal in shape. This is particularly ofadvantage in the production of catalysts wherein particle porosity anduniformity are desirable.

T he apparatus of the present invention is not limited to the productionof granulated materials alone. For example, it can be used to producetreble superphosphate directly from phosphate rock. in accordance withthis invention, I am enabled to react the phosphate rock with phosphoricacid to produce treble superphosphate. Contact of the acid and the rockis handled as part of the granulation process so that the entireoperation is completed within a matter of a few minutes.

Briefly stated, the invention contemplates an apparatus for mixing thefine solid to be granulated with sufficient liquid to form a stickyplastic mass. With a ten tilizer or fertilizer material, the liquid maybe water, an acid such as sulfuric, nitric or phosphoric acid, or amixture of these, liquid ammonia, an ammonia solution, an ammonium saltor nitrate salt solution, or other compatible liquid. The liquid andsolid components are mixed to form a plastic mass while a portion of themass is withdrawn, formed into spheroids which are returned and mixedinto the mass. The mixing of the liquidsolid mass and the formation ofthe spheroids is continued until the entire mass is composed ofspheroids of a desired and substantially uniform size.

The apparatus of this invention may be in various forms and hereinafterI have disclosed two diiferent forms which I have utilized successfully,one being directed to use along a batch line, while the other is usefulfor continuous practice of the invention.

it is in general the broad object of the present invention to provide anovel apparatus for converting a finely divided solid material intogranules of a desired size.

A further object of the present invention is to provide ill) a novelform of apparatus which can be employed for the granulation of materialssuch as fertilizers.

The invention includes other objects and features of advantage, some ofwhich, together with the foregoing, will appear hereinafter wherein thepresent preferred manner of practicing the invention is set forth,together with the disclosed apparatus.

Figure 1 is a plan view of one form of the device embodying the presentinvention.

Figure 2 is a front elevation view of the device shown in Figure 1.

Figure 3 is a right-hand elevation view of the device shown in Figure 1.

Figure 4 is a rear elevation view of the device shown in Figure 1.

Figure 5 is a side elevation, partly in section, taken through thedevice shown in Figure 1, along the line 55.

Figure 6 is a plan view of the bearing mounting used in the device ofFigure 1.

Figure 7 is a View taken along the line '7-7 in Figure 6.

Figure 8 is a view showing opening of the door structure on the front ofthe device shown in Figure 1.

Figure 9 is a section taken through the cylinder and piston structureutilized for tilting of the device shown in Figure 1.

Figure 10 is a section taken through a portion of the bearing mounting.

Figure 11 is a side elevation of an apparatus for continuous use in themanufacture of fertilizer and other materials.

Figure 12 is a side elevation view with portions of the apparatus beingshown in section.

Figure 13 is an end elevation view taken from the charging end of thedrum with the feed hopper omitted to facilitate illustration.

Figure 14 is a section taken along the line 14l4 in Figure 12.

Figure 15 is a section taken through the device and showing the trunnionrollers for supporting the drum for rotation and the end thrust rollers.

Figure 16 is a plan View of a rotor blade.

Figure l7 is a modified form of apparatus including means forcontrolling the quantity of material subject to granulation.

Figure 18 is a schematic view of the control means and system utilizedin the apparatus shown in Figure 17.

The device shown in Figure 1 is mounted upon a base framework 6 havingvertically extending standards 7 on each side thereof, upon which aremounted bearings 8. A cylindrical housing, generally indicated at 9, hashorizontal supports iii provided diametrically and from which stubshafts 12. extend into the bearings 8.

To tilt the device when desired and for reasons which will be furtherexplained hereinafter, a cylinder-piston structure, generally indicatedat 15 (Figures 2, 3 and 9) is mounted between frame t5 as at 14- and astub shaft 16 at the rear of the housing 9. To enable the structure tobe tilted selectively, the piston and cylinder structure 13 is, inefiect, provided by two separate cylinders 17 and is joined together bytie rods 1% extending through the several cylinder end closures 21, 22,23 and 24, as appears in Figure 9. A piston ructure 26, mounted upon apiston rod 27, is mounted within cylinder 17 and extends through asuitable stulling gland 28 to mounting 14 upon frame 6.

A piston structure 29 is mounted upon a piston rod 31 in cylinder 13 andextends through a stufiing gland 32, to stub shaft 16 which is, in turn,secured to the rear of the housing 9. Suitable passages 33 and 34 areprovided respectively in cylinder ends 22 and 23 and fluid isselectively supplied through these passages by means not shown, underthe control of an operator, to provide fluid injection or release frombetween the respective pistons and cylinders in which they are mountedto tilt the device selectively.

Several extreme positions of adjustment are possible, as follows:

When the pistons 26 and 29 are each closely adjacent closures 22 and 23,the housing is tilted upwardly along line AA in Figure 3, so its frontend is raised.

When the piston 26 is closely adjacent closure 22 and piston 29 isclosely adjacent closure 24-, the housing is horizontal, as in Figure 3.

When the pistons 26 and 29 are respectively located in close proximityto closures 21 and 24, the housing is tilted downward along axis 3-8 andits front end is lowered for discharge.

Mounted for rotation within the stationary housing 9 is a rotatablecylindrical structure gen rally indicated at 36 (Figure 5), including acentral cylindrical portion 37 and a frusto-conical end 38. A ring 39 ismounted upon the frustoconical portion 38, the ring being supported uponthree spaced bearings 41 mounted upon end wall 42 on housing 9; thissupports the drum 36 for rotation on one side of housing 9. To supportthe drum for rota lion when it is tilted with the frusto-conical endlowermost, bearings 103 (Figure 7) are each mounted on an arm 109 whichis, in turn, carried on a plate 111; two plates are provided and aresecured by screws 112 to the end wall 42, the arm 109 extending throughan aperture 113 in the end wall 42. Screws 114 enable the plate to beheld in a desired spaced relation to the wall to support the bearings108 in a desired engagement with the forward face of ring 39. Drum 36 isclosed by end wall 43, the latter having a driven ring gear 44 mountedthereon. Three spaced bearings 46 are mounted upon end wall 47 of thehousing 9 and fit within the ring gear to support the other end of thedrum 36 for rotation.

A drive gear 51 is provided in mesh with the ring gear 44, gear 51 beingmounted upon a shaft 52 which extends through the end wall 47 into aspeed reducer, generally indicated at 53 (Figure 1), the latter beingdriven by a motor 54 mounted upon a suitable support structure generallyindicated at 56 (Figure 3) on end wall 47.

The openings provided in the end wall 42 of structure 9 and in the drum36 are closed by a door structure generally indicated at 61, the latterbeing mounted upon an arm 62 fixed on an end of shaft 63 journaled inbearings 64 mounted upon end wall 42 of the housing 9 (Figures 1, 2, 3and 8). The other end of shaft 63 includes an arm 66 engaged with apiston rod 67 extending into a piston cylinder structure generallyindicated at 653, the latter being hinged as at 69 upon the top of thedrum 9. When fluid is supplied suitably to the pistoncylinder structure68, the door 61 can be opened and closed selectively, as desired. Thedoor structure includes a separate, rotatable plate 7 and a fixed plate7d engaging the aperture in the housing 9, while the rotatable plate 71engages the opening in drum 36 (Figure 8).

To seal the door structure 61 against material loss, the frusto-conicalend 38 on the cylindrical structure 36 is provided with a ring 303having a hard metal face thereon and which rotates in engagement with aring 305 having a like face and provided on annulus The annulus 304 issupported on four studs 366 and is urged (Figures 2 and 5) by springs387 to maintain the hard face on the attached ring 3-35 in engagementwith the like face on ring 393.

A cutter bar 361 is mounted on the inner face of door 61 to rotatewithin rings 333 and 3% and annulus 3G4 and so keep the door free ofmaterial. An hydraulically operated motor 302 is mounted on the door 61on arm 62; the motor swings the cutter bar 301 through an arc of atleast 180.

Mounted centrally within the drum 36 for rotation therein is a rotorblade structure, generally indicated at til 81 (Figures 5 and 10), andwhich includes a central shaft 82 extending through a bearing structure,generally indicated at 83, and which is presently described in detail.Shaft 8-2 extends from the bearing structure 83 of the rear of housing 9and carries several pulleys 84 thereon. Belts 36 are trained aboutpulleys 84, and about pulleys 87 on electric motor shaft 88, theelectric motor 89 being mounted upon supporting bracket structure 21 onthe rear of the housing 9, as is shown in Figure 4. The motor shaft 38and central shaft 82 can be provided with suitable pulley sheavesenabling the speed of rotation of shaft 82 to be controlled as desired.

Bearing 83 is made up of a tubular member 101, which extends through endwall 47 of the drum 9 and is secured thereto by triangular supportelements 102, build"! are Welded between the end wall 4-7 and thecylindrical member till. Suitable seals and thrust-bearings (not shown)are mounted in the cylindrical member to support the shaft 32; lubricantis supplied as through fitting 163. One end of cylindrical member 101 iswelded to a ring 166 which, in turn, fits the end wall 43 snugly, arubber sealing ring 107 being provided between the two. Ring 196 isclosed by a plate 114 secured in place by cap screws 116. Welded uponthe plate is a cutter bar, generally indicated at 117 and which, as isshown in Figure 5, fits closely adjacent to and 'tends upwardly alongthe end wall 4-3, across cylindrical member 37 and downwardly alongfrustoconical portion 38 and outwardly through the opening in drum 9,being secured in place by studs 118 upon a bracket M2, the latter beingin turn secured by studs I123 to the end wall 42.

Mounted upon the end of shaft 82 is a closure plate 122, the latterhaving a tongue and groove seal, as indicated at 123, with plate 114(Figure 10).

The forward end of shaft 82 is threaded as at 126, and a out 127 isprovided thereon to retain in place a spool structure generallyindicated at 128, which includes a plurality of spaced annular members129 extending about the spool, the spool fitting snugly against ashoulder 131 provided upon shaft 82. The several rotor blades 133 areeach mounted between the spaced annular members 129 on rods 132, whichextend through the several annular members 129 to provide a support therotor blades, the blades being thus mounted for limited oscillation uponthe rods and with respect to shaft 82. Referring particularly to Figures5 and 10, it will be noted that the rotor blades 133 are arranged inrows extending parallel to the longitudinal axis of the shaft 82, theblades in each row being arranged in a closely spaced relationship withtheir faces parallel, thus providing a relatively narrow slot betweenadjacent blade pairs through which material may pass when thrown intothe rotor blade structure 81 from the cutter bar 301. The material incontact with a fiat face of a blade rolls across such flat face and sois formed into a ball.

The rotor-blades can readily be removed and replaced with others byremoving nut 127 from the threaded end of shaft (52, release of the nutpermitting removal of closure annular plate 136 and of the several rods13?. whereby the rotor blades can be removed readily and replaced withothers, as desired.

A charge of a suitable material to be granulated is placed in the drumwith the latter horizontal or tilted slightly to admit the charge,together with a sufficient source of moisture such as water, acid orother liquid. The drum is then tilted to approximately line AA.

When the drum is rotated, it will be found that the mixture quicklybecomes gummy and mastic and would stick to the wall of the housing 36except for the presence of the cutter bar H7 (Figure 5), which cuts thetutorial off the drum as it rotates and drops down into the rapidlyrotating rotor-blades. by observing the power consumption of the motor.one will find that during the gummy, mastic stage, the material requiresconsiderable power to break it up into relatively small masses, but asthe material dries somewhat and forms into round balls, the powerrequirement decreases considerably. When the stage of optimum particlesize is reached, the drum is tilted counter-clockwise to discharge itscontents.

In Figures 11 through 15 in the drawings, a continuous unit is shown,one wherein the material is fed in continuously at one end of a rotatingdrum and is withdrawn from the other end of the drum in finishedpelleted form. This device includes a suitable framework, generallyindicated at 201, providing a base for a stationary cylindrical housing2G2. At its inlet or feed end, the drum 202 includes a suitable partialend closure 203, having a bracket 294 thereon upon which is mounted abearing 2%. At its outlet end, the drum includes an end closure 2027having a bracket secured thereon and providing a mounting for a bearing209.

A cylindrical drum 211 is supported and mounted for rotation within thestationary housing 2&2, this support being provided by two sets of threespaced trunnions 21 2 (Figure 15), each trunnion set being provided atspaced points about the drum 212 and engaging one of the pair of flanges213 secured to the drum 2l1 at oppo site ends thereof. A thrust bearing,generally indicated at 214, is mounted upon the side of the cylinder 292and includes a rotatable wheel 216 riding against that face of each ofthe flanges 213 which is toward the outlet end of the drum to take upthe thrust provided by the drum 211 during rotation.

Mounted for rotation within the drum 211 is a rotor structure, generallyindicated at 221, mounted upon a shaft 222, the latter being mounted forrotation in bearings 2% and 209. Shaft 222 includes a V-belt pulley 27 3at one end thereof, a plurality of V-belts 224 being extended about thepulley 223 and a pulley 226 on motor shaft 227. The motor shaft extendsfrom motor 228 which is mounted upon a framework, generally indicated at229, upon the top portion of the housing 202.

Drum 211 is driven by a motor speed reducer unit generally indicated at231 and which is in turn mounted upon a bracket 232, carried upon theframe 22 upon the top of drum 202. A \l-belt 234 is extended about apulley 236 on the motor speed reducing unit 231, and about a pulley face240 on the drum 211, as is shown in Figures 12 and 13.

Supported on bracket 208 and on the upper side of the end closure 2% ofthe drum 202 is a cutter blade 261, fitting closely each of the endclosures of the drum 2H and the internal surface of the drum so thatmaterial carried by the drum is cut off and dropped down into the rotoras the drum 211 is rotated.

The rotor 221 is made up of a plurality of cutting bladed elements 241;each element includes a central annular hub 242 fitting shaft 222 andhaving, in the form shown, eight radial blades 243. Spacers 244 aremounted between adjacent elements and the assembly is retained togetheras a unit by a plurality of rods 246 extended between collars 247 ateach end of shaft 222. The assembled elements are retained in place onthe shaft by the square retainer blocks 248 which clamp about the shaftand against the collars 247 by bolts 249. it will be noted that each of.rods 246 is positioned opposite one of the square faces on the retainerblocks 243 so that any one of the rods can be withdrawn selectively uponloosening of the nuts on its ends without disturbing one of the otherrods. This construction enables the blades to be readily repaired orreplaced. Referring particularly to Figures l2, l5 and 16, it will benoted that the rotor blades 243 are arranged in rows extending parallelto the longitudinal axis of the shaft 222, the blades in each row beingarranged in a closely spaced relationship with their faces parallel,thus providing a relatively narrow slot between adjacent blade pairsthrough which material may pass when thrown into the rotor bladestructure 221 from the cutter bar 261. The material in contact with aflat face of a blade, rolls across such fiat face and so is formed intoa ball.

Various modifications are possible in the rotor and its operation. Forexample, the rotor blades can be fixed on the supporting shaft or can befree to swing through a limited range. The fixed type of blade ispreferred because it is less expensive to construct and is free of thewear which occurs on the supports for the swinging blades. In addition,the rigid hammers require less power; for example, in a batch machineoperating on a oiO-pound batch of acid and phosphate rock to manufacturetreble superphosphate, 20-22 kw.-h. were required to rotate the swinginghammers at 950 R. P. M. as against 15--l6 kw.-h. to rotate the fixedblade hammers at the same speed, that is, 950 R. P. M.

The rotor can rotate with the drum or in the opposite direction. Theformer type of operation is preferred because the total power inputrequired is less when the drum and rotor rotate in the same direction.

in a batch device, one can stop the rotor after the machine has been inoperation for some minutes and just before dumping. This has the effectof reducing undersize material for the pellets roll up on themselvesinto pellets of a larger size. If they become too large, a few secondsrotation of the rotor will break them down to small size. The sameeffect can be attained in a continuous machine by having a short spaceat the discharge end of the rotating drum which is, free of the rotorblades.

An inlet hopper, generally indicated at 2511, is provided at the inletend 203 of the drum 2ii2, and material to be processed in the drum canbe delivered thereto as by conveyor belt 252. Material issuing from thedrum 202 spills out over the annulus 257 providing an end on drum 211and thence onto another conveyor belt or onto a pile, as desired.

In operation, the subframe 201 is supported by suitable means, generallyat a slight angle to the horizontal so that the inlet end of the drum211 is elevated at an acute angle with respect to the outlet end. Theangle of the drum is varied with the material processed and with theretention time of material desired for processing of a given material.For example, with the drum 211 six feet in length and three feet indiameter, rotating at a speed of 22 R. P. M. and with the rotor 221having an overall diameter of 29" and rotating at a speed of 800 R. P.M., phosphate rock and acid was retained for between 45 to 60 seconds,the drum being at an angle of 3 to the horizontal. The drum angle canvary usually between about 3 and 10, depending on the load and theretention time desired.

The angle of inclination of drum 211 can be altered to maintain a massof constant weight in the drum. This is of advantage in ensuringconstant quality control on the product. In Figures 17 and 18, l haveshown the inlet end of drum 211 supported by stub shafts 261 in brackets262 mounted on frame 2&1. The outlet end of the drum is supported bystub shafts 263 engaged with links 264 which are joined to one of endpistons 266. Cylinders 2&7 are mounted on the frame 2% and support eachpiston in position to raise and lower the outlet end of the drum. Thelower end of each cylinder is connected to a common pipe 268 which is inturn connected to a constant pressure control regulator 269. Fluid underpressure is supplied from reservoir 271 by pump 272 through line 270,while fluid is returned through line 273 from the regulator 22% to thereservoir. The regulator 269 is so adjusted that if the total load inthe drum increases, fluid is released from the cylinders 267 and thedrum angle is lowered to release material until the desired load isattained. If the load in the drum decreases, fluid is supplied to thecylinders until the drum load again applies the desired pressure on theregulator.

The apparatus described can be utilized to manufacture variousfertilizer materials as follows:

Example l.-Utilizing a drum having a diameter of two feet and rotated ata speed of 176 feet per minute with a rotor 16" in diameter rotating at1750 R. P. M., materials having the following screen analysis wereobtained upon a single superphosphate made from Montpelier, ldaho,phosphate rock and taken directly from the den with no added moisture;each charge weighed 65 pounds.

Percentage Screen Size Retention time in mixer Percent in secondsmoisture Screen analysis Percent +4 mesh 5 4+20 mesh 80 20 mesh 15 Themesh material was not dusty and was in the form of individual particles.

The material was dried immediately; chemically, the material analyzed asfollows:

I H i Insoln i38 l i iiib i F. A. \loistu e s P205 1 i i l PercentPercent Percent l Percent Percent 46.6 3 43.6 V 4.8 5.7

The conversion was 79%; the available P205 content was 45.2% on thebasis of a moisture content of 2.5%.

Example 1ll.Utilizing a batch machine with a drum 49 in diameter,rotating at 18 R. P. M., with a rotor of diameter having 36 blades androtating at 750 R. P. M., the following results were obtained on a 650pound batch of Sage A-bed rock having a 13% moisture content and using7373.5% phosphoric acid at 125-] F. and a P205 acid to rock ratio of 2.3to 2.4. The total time in the drum was eight to nine minutes, allowing90 seconds for charging and 30 seconds for dumping.

Example I V .The apparatus of Example III was used to pelletizepreviously mixed acid and rock mixtures which had been aged thirty daysin the case of the Sage A-bed rock, and seven to eight days in the caseof the Sage Beneficiated Rock. Data and conclusions are tabulated asfollows:

Analytical data on the pile material was as follows:

File No Pile No. Pile No. 1-Sage 2-Sage- 3-Sage- A-Bed Bene. Bene.

Rock P205, percent 31 32 32 Rock R205, Percent ..2. 5 3.0 3.0 no,acid/rock 2. 4 2. 4 2. 3 Age of pile, d 30 7 8 Pile Analysis l 'lTotalP205, pereent 47. 2 48. 0 47. 6 Insoluble P205, percent.. 1. 8 1. 7 2.0Available P105, percent... 15.4 46. 3 45. 6 Free acid P205, percent...2.0 3. 5 3. 2 Moisture, percent G. 2 5. 0 5. 2 Resid, cone. HaPO4,percent: 39 65. 5 62. 4 Percent conversion S6. 9 87. 8 86. 0

Example V.1,000 pounds of phosphate rock containing 31.5% P205 wasweighed into a batch hopper, while 1,450 pounds of phosphoric acid(72.5% H3P04) were weighed out; the acid was preheated to a temperatureof 135140 C. The material was then discharged into a drum of the type ofExamples I-IV, but of larger capacity, along with 280 pounds of oversizerecycle material which had been reground in a hammer mill and 350 poundsof undersize recycle material. The drum 36 was then rotated for nineminutes, following which the material was discharged. It amounted to3,070 pounds of product having a moisture content of 9.5%, a free acidcontent as P205 of 7.5%, an available P205 content of 43.5%, and a totalP205 content of 45.5%. The material Was then dried in a rotary gas-fireddrier wherein the material was passed in parallel fiow to a hotcombustion gas, the material issuing from the drier at a temperature ofl-200 F., while the gas temperature was approximately 300 F. Thematerial was then cooled in a rotary air cooler to l20-l25 R, followingwhich it was held on a storage pile for from two to three weeks. Thematerial from the storage pile then had a P205 content of 47-48 anavailable P205 content of 45.5-46.5%, from 3% to 4% moisture and from 2%to 3% of free acid as P205. This material was screened and that materialwhich passed a ZO-mesh screen and that material which was retained on anS-mesh screen were returned for admixture to a later batch, there being350 pounds of the undersize material and 280 pounds of the oversizematerial. The final product amounted to ..,3l5 pounds and was of a sizesuch that it would all pass an 8-mcsh screen and be retained on a20-mesh screen. It contained 48% P205, 46% of available P205, 34%moisture, and had a free acid as P205 of 23%.

Example Vl.The equipment of Figures 1-10 and Example V can also be usedto pelletize previously aged single super-phosphate. As typical of thisoperation, 1,000 pounds of aged single superphosphate was taken from apile, the material having an available P205 content of 18%. The materialwas crushed to 1" to 2" lumps and was then introduced into the drum 36along with approximately 40 pounds of water, pounds of undersizematerial, and 200 pounds of oversize material which had been reground ina hammer mill. The material was mixed in the batch pelletizer for threeminutes and was then discharged into a rotary gas fired drier, whereinit passed in parallel flow with a hot combustion gas, approximately 40pounds of water being driven oh", and the material having a final exittemperature of 180200 F. It was then cooled in a rotary air cooler to120-125 F and passed over a screen wherein material coarser than S-meshand finer than 20-mesh was removed, there being 200 pounds of largerthan 8-mesh material and 100 pounds of the smaller than 20-meshmaterial. The product amounted to 1,000 pounds having an 18% availableP205 content, the product being uniform spheroids of substantiallyuniform texture in cross-section. The oversize material was crushed in ahammer mill and was then returned to the drum 36 while the undersizematerial was fed directly to the drum 36 with another batch.

Example VH.-The continuous drum device of Figures 11-16 can also beutilized to produce a fertilizer material as desired. For example, toproduce pelletized single superphosphate, 1,000 pounds per hour ofmilled superphosphate having an 18% available P205 content was fed intoa continuous pelletizer along with 80 pounds of water per hour, 120pounds over oversize material finer than ZO-mesh. The drum was thatpreviously described in connection with Figures 1116. The material waspassed through the continuously rotating drum 211 which had a retentiontime of approximately one minute. The material issuing from the drum waspassed into a rotary drier wherein it passed in parallel flow with a hotdrying gas at such a rate that approximately 60 pounds of water wereremoved from the material and the material issued from the drier at atemperature of 180 200 F. The product was then cooled in a rotary airdrier to 120-l25 F. and screened to remove material coarser than 8-meshand finer than ZO-mesh, the production amounting to 1,000 pounds ofmaterial per hour having 18% available P205 content, and a moisturecontent of 6%; by drying the material to a 3% free moisture content, theavailable P205 content was increased to 19%. To provide an ammoniatedsuperphosphate, 1,000 pounds per hour of previously ground and agedsuperphosphate was dropped down a vertical pipe of relatively narrowsection while pounds per hour of anhydrous ammonia were introduced intothe bottom of the pipe, this serving to neutralize free acid present inthe superphosphate and convert dicalcium phosphate partially tomonocalcium phosphate. The resulting material was then fed into thecontinuous drum along with 180 pounds per hour of previously groundoversize material and 450 pounds per hour of undersize material. Inaddition, 50 pounds per hour of water and 130 pounds per hour of anammonia solution containing 20% nitrogen were properly sprayed in at theinlet end of the continuous drum. The drum had a retention time ofapproximately one minute. The material issuing from the pelletizer wasthen passed into a rotary drier wherein it was passed in parallel flowto a hot drying gas, 200 pounds per hour of water being driven oil, andthe material issuing from the drier at approximately 180200 F. It wascooled in a rotary air cooler to 120l25 F. and then passed over a screento eliminate material coarser than S-mesh and finer than 20- mesh. Theresulting product, amounting to 925 pounds per hour, had a 17% availableP205 content, and a 4% nitrogen content. If desired, the undersizematerial can remain in the product since it is merely fine pellets.

Example VHI.-ln the manufacture of triple superphosphate, 1,000 poundsper hour of phosphate rock having 31-32% available P205 content wasintroduced into a mixer discharging into a continuous rotary den alongwith 1,450 pounds per hour of crude phosphoric acid containing 72-73%HsP04, the acid being at a temperature of 135-140" F. Also fed to theden by addition to the acid-rock mixer were 460 pounds of undersizematerial and 350 pounds of oversize material, the latter having beenground in a hammer mill prior to addition to the mixer. The materialremained in the den for approximately ten to twelve minutes, followingwhich it was cut out and removed, being fed into the describedcontinuous drum 211 along with 30 pounds of water'per hour. The materialremained in the drum for approximately one minute, the total feed rateto the drum being 3,290 pounds of material per hour. The product issuedfrom the pelletizer at l50160 F.; it amounted to 3,270 pounds ofmaterial per hour having a total P205 content of 45-46%, a free acidcontent of 78%, and contained from 9-10% moisture.

The material was then passed into a parallel-flow gas fired drierwherein 200 pounds of water were driven oil, the material issuing fromthe drier at 180-200 F. and being cooled in a rotary air cooler to 125F. It was then permitted to remain on the storage pile from two to threeWeeks, following which it was screened to remove over and undersizematerial. The resulting product, of a size between -8 and +20 mesh,amounted to 2,315 pounds and had a total P205 content of 48%, anavailable P205 content of 46%, a moisture content of 34%, and. a freeacid content of 2-3% as P205. If deemed desirable, this product can bedried further to reduce the moisture content and so tip-grade thematerial.

The previously described drum 211 was employed to pelletize treblesuperphosphate taken from a continuous den. The drum was 36" in diameterand six feet long, roating at 22 R. P. M.; the rotor was 29" in diameterand was rotated at 800 R. P. M. The material was fed to the drum at therate of 1112 tons per hour. The phosphoric acid contained 72% P205 andwas heated to a temperature of -140 F. The ratio of acid feed to rockwas 2.3 to 2.4 on a P205 basis. The material was retained in the den forfrom twelve to fourteen minutes; the (llll't had slope of approximately33 and retained the material for approximately 60 seconds; thethreeblades at the front and at the rear of the rotor were absent. Water wassupplied to the drum between 0.8 and 1.3 gallons per minute. Thematerial had an average particle size such that 12% was retained on a6-mesh screen, 82% passed a 6-mesh screen and was retained on a ZO-meshscreen,

and 6% passed the 20-mesh screen.

In another operation, but utilizing all rotor blades and a slightlyhigher. pelletizer Water feed of 1.5 to 2.0 gallons per minute, thematerial produced was of a size such that 13% was retained on an 8-meshscreen, 62% passed the 8-mesh screen but was retained on a 20-meshscreen, while 25% passed the 20-nesh screen.

While in the foregoing l have dealt with fertilizer materials, it willbe obvious to those skilled in the art that other materials can beutilized and can be successfully formed into spheres of a desired sizeby coordinating the ratio of solid material, liquid, drum speed androtor speed. One can readily determine the correct operating condi tionsfor any given material and for any given rate of feed if one observescertain basic operating principles in connection with the machine andprocess involved. Thus, the rotating drum acts as a continuous feederfor the high speed rotor, while the rotor throws material oiltangentially against the drum with such force that if any portion of themass discharged against the drum is not well mixed or is too wet, itwill become plastered against the side wall of the drum, which thencarries it around to the cutter bar. The cutter bar cuts the maerialfrom the drum and drops it back into the rotor. This operation iscontinued until the mass is or a uniform plasticity. The three elements,the drum, the rotor, and the cutter bar cooperate to achieve thoroughand uniform plasticity in the material. As the material attains auniform plasticity, the rotor blades striking the plastic material formthe material into spheroids, the wet plastic material rolls across theblades of the rotor and is so formed into spheroids. As the operation iscontinued, the rolling, cutting, and sphere-forming action continuesuntil the mass is of a desired plasticity and size of spheroid.

I claim:

1. In a device of the character described, a drum,

means supporting the drum for rotation about the axis of rotation of thedrum, a cutter bar extending along in close proximity to the innersurface of the drum adjacent the top of the drum to cut materialadhering to the drum wall and release it for a free gravital fall insaid drum, and a plurality of cutter blades supported for rotation insaid drum to receive said material falling in the drum after cuttingfrom the drum by said cutter bar, said plurality of cutter blades beingmounted radially and in rows with adjacent blades in each row spacedapart to rovide a relatively narrow passageway for material between saidadjacent blades.

2. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, a cutter bar extendingalong in close proximity to the inner surface of the drum adjacent thetop of the drum to cut material adhering to the drum wall and release itfor a free gravital fall in said drum, a plurality of cutter bladessupported for rotation in said drum to receive said material falling inthe drum after cutting from the drum by the cutter bar, said pluralityof cutter blades being mounted radially and in rows with adjacent bladesin each row spaced apart to provide a relatively narrow passageway formaterial between said adjacent blades, means for rotating the drum atone speed, and means for rotating the cutter blades at a second speedseveral times said one speed.

3. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, means for feedingmaterial into the drum at one end thereof, a cutter bar extending alongthe inner surface of the drum adjacent the top of the drum and in closeproximity to the drum to cut material adhering to the drum wall andrelease it for a free gravital fall in said drum, a plurality of cutterblades supported for rotation in said drum and to receive said materialfalling in the drum after cutting from the drum by said bar, saidplurality of cutter blades being mounted radially and in rows withadjacent blades in each row spaced apart to provide a relatively narrowpassageway for material between said adjacent blades, and means forremoving material from the other end of the drum.

4. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, means for feedingmaterial into the drum at one end thereof, a cutter bar extending alongand in close proximity to the upper surface of the drum and parallel tosaid axis to cut material adhering to the drum wall and release it for afree gravital fall in said drum, a plurality of cutter blades supportedfor rotation in said drum and to receive said material falling in thedrum after cutting from the drum by said bar, said plurality of cutterblades being mounted radially and in rows with adjacent blades in eachrow spaced apart to provide a relatively narrow passageway for materialbetween said adjacent blades, means tor rotating the drum at one speed,means for rotating the cutter blades at a second speed which is severaltimes said one speed, and means for removing material from the other endof the drum.

5. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, means for feedingmaterial into the drum at one end thereof, a cutter bar extending alongand in close proximity to the inside of the drum adjacent the top of thedrum to cut material adhering to the drum wall and release it for a freegravital fall in said drum, a plurality of cutter blades supported forrotation in said drum and to receive said material falling in the drumafter cutting from the drum by said bar, said plurality of cutter bladesbeing mounted radially and in rows with adjacent blades in each rowspaced apart to provide a relatively narrow passageway for materialbetween said adjacent blades, means for rotating the drum at one speed,means for rotating the cutter blades at a second speed which is severaltimes said one speed, means for removing material from the other end ofthe drum, and means for tilting the drum to raise and lower one end ofthe drum with respect to the other end of the drum to control the weightof material retained therein.

6. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, a cutter bar extendingalong in close proximity to the inner surface of the drum adjacent thetop of the drum to cut material adhering to the drum wall and release itfor a free gravital fall in said drum, and a plurality of cutter bladessupported for rotation in said drum in a spaced relation to at least oneend of the drum to receive said material falling in the drum aftercutting from the drum by said cutter bar, said plurality of c tierblades being mounted radially and in rows with r ent blades in each rowspaced apart to provide a relatively narrow passageway for materialbetween said adjacent blades.

7. In a device of the character described, a drum, means supporting thedrum for rotation about its longitudinal axis, a cutter bar extendingalong in close proximity to the inner surface of the drum adjacent thetop of the drum to cut material adhering to the drum wall and release itfor a free gravital fall in said drum, a rotor extending parallel tosaid axis and supported for rotation in said drum to receive saidmaterial falling in the drum after cutting from the drum by the cutterbar, said plurality of cutter blades being mounted radially and in rowswith adjacent blades in each row spaced apart to provide a relativelynarrow passageway for material between said adjacent blades, means forrotating the drum at one speed, means for rotating the rotor at a secondspeed at least several times said one speed, the rotor including aplurality of radially extending cutter bars fixed on the rotor.

8. In a device of the character described, a drum, means supporting thedrum for rotation about its longi' tudinal axis, means for feedingmaterial into the drum at one end thereof, a cutter bar extending alongin close proximity to the inner surface of the drum adjacent the top ofthe drum to cut material adhering to the drum wall and release it for afree gravital fall in said drum, a rotor including a plurality of cutterblades mounted radially on the rotor and in rows thereon with adjacentblades in each row spaced apart a distance sutficiertt only to provide arelatively narrow passageway for material between adjacent blade pairs,means supporting the rotor for rotation in said drum and to receivematerial falling in the drum after cutting from the drum by said bar,and means for removing material from the drum.

9. In a device of the character described, a drum having a longitudinalaxis, means supporting the drum for rotation about said axis in onedirection, a cutter bar extending along the inner surface of the drumadjacent the top of the drum to cut material adhering to said innersurface and release the material for a free gravital fall, a rotorsupported parallel to said drum longitudinal axis, means for rotatingthe rotor in the drum, the rotor having a plurality of radiallyextending cutter blades thereon extending along the rotor in rows fromsubstantially one end of the drum to the other end of the drum, saidblades each having a flat planar face extending parallel to the plane ofrotation of the blades, adjacent blade pairs in each row being spacedapart only a distance sufiicient to provide a relatively narrowpassageway for material tween said adjacent blade pairs.

10. A device as in claim 9 wherein the cutter blades are hinged on therotor.

11. A device as in claim 9 wherein the cutter blades are fixed on therotor.

12. In a device of the character described, a cylindrical drum having alongitudinal axis; means supporting said drum with said axissubstantially horizontal; a rotor having a longitudinal axis extendingsubstantially parallel to the axis of the drum, said rotor having aplurality of radially extending cutter blades mounted thereon in rows,

the cutter bar means effective to cut material adhering to the druminner surface free of said inner surface and to deliver said outmaterial by gravital fall into said rotor.

13. In a device of the character described, a cylindrical drum having alongitudinal axis; means supporting said drum with said axissubstantially horizontal; a rotor having a longitudinal axis extendingsubstantially parallel to the axis of the drum, said rotor having aplurality of radially extending cutter blades mounted thereon in rowsextending parallel to the longitudinal axis of the rotor,

each blade having opposite flat faces thereon extending parallel to therotational path of the rotor and being close- 1y adjacent to oneanother; means supporting the rotor for rotation about its longitudinalaxis; cutter bar means mounted closely adjacent to the inner surface ofthe drum to cut material adhering to the inner surface of the drum;means for moving the drum and cutter bar relative to one another torender the cutter bar means effective to cut material adhering to thedrum inner surface free of said inner surface and to deliver said cutmaterial by gravital fall into said rotor; and means for rotating therotor at a speed which is at least several times that of cutter barrelative to the drum.

14. An apparatus for forming a damp mixture into small finely dividedfree-flowing pellets; the apparatus comprising a cylindrical drum havinga longitudinal axis; means supporting the drum with its longitudinalaxis substantially horizontal; means for feeding materials into the drumto provide therein a damp mass tending to adhere to the inner surface ofthe drum; a rotor for forming the damp material in the drum into smallfinely divided free-flowing pellets, said rotor having a longitudinalaxis, means supporting the rotor for rotation with its longitudinal axissubstantially parallel to the longitudinal axis of the drum, said rotorhaving a plurality of rows of blades thereon with the blades in each rowextending radially to the longitudinal axis of the rotor, each bladebeing substantially rectangular in transverse section and havingopposite parallel flat faces extending parallel to a plane normal to thelongitudinal axis of the rotor, the blades in each row being arrangedwith adjacent faces spaced apart to provide only a narrow space betweenadjacent blades through which material undergoing formation into pelletspasses in engagement with the adjacent blade faces defining said narrowspace; and means for cutting material adhering to .the

drum inner surface from said surface and for delivering said material bygravital fall into said rotor for pellet formation.

15. An apparatus for forming a damp mixture into small finely dividedfree-flowing pellets; the apparatus comprising a cylindrical drum havinga longitudinal axis;

means supporting the drum with its longitudinal axis substantiallyhorizontal; means for feeding materials into the drum to provide a dampmass normally adhering to the inner surface of the drum; a rotor forforming the damp material in the drum into small finely dividedfree-flowing pellets, said rotor having a longitudinal axis, meanssupporting the rotor for rotation with its longitudinal axissubstantially parallel to the longitudinal axis of the drum, said rotorhaving a plurality of rows of blades thereon with the blades in each rowextending radially to the longitudinal axis of the rotor, each bladebeing substantially rectangular in transverse section and havingopposite parallel fiat faces extending parallel to a plane normal to thelongitudinal axis of the rotor, the blades in each row being arrangedwith adjacent faces spaced apart to provide only a narrow space betweenadjacent blades through which material undergoing formation into pelletspasses in engagement with the adjacent blade faces defining said narrowspace; and means movable relative to the inner surface of the drum forcutting material adhering to the drum inner surface from said surfaceand for delivering said material by gravital fall into said rotor forpellet formation; the peripheral speed of rotation of the rotor bladesbeing at least several times that of the cutting means relative to thedrum inner surface.

16. An apparatus for forming a damp mixture into small finely dividedfree-flowing pellets, the apparatus comprising a cylindrical drum havinga longitudinal axis; means supporting the drum with its longitudinalaxis substantially horizontal; means for feeding material into the drumto provide a damp mass normally adhering to the inner surface of thedrum; a rotor for forming the damp material in the drum into smallfinely divided free-flowing pellets, said rotor having a longitudinalaxis, means supporting the rotor for rotation with its longitudinal axissubstantially parallel to the longitudinal axis of the drum, said rotorhaving a plurality of rows of radial blades thereon, each blade havingopposite parallel fiat faces extending parallel to a plane normal to thelongitudinal axis of the rotor, the blades being arranged with theirrespective adjacent faces spaced apart to provide only a narrow spacebetween adjacent blades through which material undergoing formation intopellets passes in engagement with the adjacent blade faces defining saidnarrow space; and means for cutting material adhering to the drum innersurface from said surface and for delivering said material by gravitalfall into the blades on said rotor for pellet formation.

17. A device as in claim 1 wherein the drum has an opening at one endthereof and wherein means are provided for supporting the drum forlimited movement between a discharge position wherein the drum axis onthe side of the opening extends below the horizontal and a granulatingposition wherein the drum axis on the side of the opening extends abovethe horizontal.

References Cited in the file of this patent UNITED STATES PATENTS1,428,920 Sturtevant Sept. 12, 1922 1,570,086 Schatier Ian. 19, 19261,980,130 Fasting Nov. 6, 1934 1,994,718 Lellep Mar. 19, 1935 2,120,540Billings June 14, 1938 2,139,584 Hunter Dec. 6, 1938 2,158,513 Lloyd May16, 1939 2,287,759 Hardesty et a1. June 23, 1942 2,293,439 Lloyd Aug.18, 1942 2,306,698 Heller Dec. 29, 1942 2,414,701 Shoeld Jan. 21, 19472,422,989 Skoog June 24, 1947 2,442,513 Sackett June 1, 1948 2,448,126Shoeld Aug. 31, 1948 2,543,898 De Vaney Mar. 6, 1951

1. IN A DEVICE OF THE CHARACTER DESCRIBED, A DRUM, MEANS SUPPORTING THEDRUM FOR ROTATION ABOUT THE AXIS OF ROTATION OF THE DRUM, A CUTTER BAREXTENDING ALONG IN CLOSE PROXIMITY TO THE INNER SURFACE OF THE DRUMADJACENT THE TOP OF THE DRUM TO CUT MATERIAL ADHERING TO THE DRUM WALLAND RELEASE IT FOR A FREE GRAVITAL FALL IN SAID DRUM, AND A PLURALITY OFCUTTER BLADES SUPORTED FOR ROTATION IN SAID DRUM TO RECEIVE SAIDMATERIAL FALLING IN THE DRUM AFTER CUTTING FROM THE DRUM BY SAID CUTTERBAR, SAID PLURALITY OF CUTTER BLADES BEING MOUNTED RADIALLY AND IN ROWSWITH ADJACENT BLADES IN EACH ROW SPACED APART TO PROVIDE A RELATIVELYNARROW PASSAGEWAY FOR MATERIAL BETWEEN SAID ADJACENT BLADES: